1. Field of the Invention
The present invention relates to a brain dysfunction and seizure detector monitor and system, and a method of detecting brain dysfunction and/or seizure of a subject. The present invention preferably is a system capable of detecting in real time the presence of epileptic activity based on recording of brainwave signal(s) such as scalp electroencephalograms (EEG) or electro-corticograms (ECoG), see FIG. 1. Both signals are used to assess brain function and are the best and most used marker for seizure activity. This system incorporates a state-of-the-art signal processing algorithm based on time-frequency decomposition of the signal, as disclosed herein. This system is intended to be used primarily in the following situations:
to help first responders such as Emergency Medical Technicians (EMTs) to diagnose the presence of epileptic activity in accident victims or patients for whom no medical information is available,
to help nursing facilities, intensive care units, emergency rooms, operating rooms etc., to monitor their patients and provide timely treatment, by automatically detecting seizure activity without the need for a trained neurologist or EEG technologist who needs to continuously monitor and interpret EEG recordings,
to help neurologists and EEG technologists review and mark long term EEG and ECoG recordings for in depth determination of seizure onset, type and location,
to provide early seizure detection for advanced therapeutics such as Deep-Brain Stimulation and other timely treatment delivery.
2. Technical Background
Detection of seizure activity in EEG and ECoG recordings has been the object of intensive research in the past 50 years. Yet, most of the clinical work in this field still involves offline review of signal tracings by expert EEG technologists trained in the recognition of patterns in the signal indicative of seizure activity.
Seizures are usually classified into convulsive and non-convulsive. Convulsive seizures can be easily observed by attending medical personnel since they involve involuntary muscle movements, convulsion, and twitching. Non-convulsive seizures, on the other hand, are more difficult to diagnose accurately, since the patient is essentially un-responsive with no outward signs of seizure activity, which may be due to a number of factors other than epilepsy. The consequence of seizure activity can be dramatic. Any lasting un-controlled seizure can provoke irremediable brain damage. Timely pharmacological intervention is necessary in order to stop the seizure and lessen the resulting injury. Pharmacological intervention usually involves sedative drugs which essentially suppress cortical activity in order to stop the seizure. This intervention is not without posing risk to the patient, as it also affects the circulatory system (bradychardia, hypotension, etc.). Thus the treatment should be closely supervised by trained medical professionals and it can be particularly risky in patients who already suffer from reduced cardiovascular reserves. It is also particularly risky to administer the treatment to patients whose medical history is not available. Having a means, such as the one disclosed in the present invention, which accurately detects and diagnoses the presence of ictal activity based on electrophysiological recordings can help medical professional in timely decision making to prescribe the adequate treatment. This can be particularly useful in emergency situations, where trained neurologists and EEG technologists may not be available.
Most epileptic patients are aware of their condition and are provided with a prophylactic treatment to control their seizures. They have already been diagnosed and carry with them identification tags which inform first responders of their medical situation in case of emergency. However, there are a number of situations for which a non-epileptic patient may have seizures: traumatic brain injury resulting from a blunt force trauma, concussion, or sudden acceleration/deceleration; poisoning from chemical agents, nerve gas, etc.; high fever. In these cases, seizures may be non-convulsive. First responders who are usually non-EEG experts need to make an accurate determination of the patient state in order to provide timely and adequate treatment. A device such as the one proposed herein answers this need.
Another problem faced by medical teams in emergency situations is drug-seeking individuals faking seizures in order to receive benzodiazepine. These pseudo-seizures are a growing problem in the U.S., where it is estimated that up to 40% of emergency admissions involving patients complaining of seizures are pseudo-seizures who then receive an inadequate treatment instead of the appropriate psychological and counseling help.
In many clinical settings such as geriatric and palliative care, emergency rooms, operating rooms, intensive care units and other hospital settings, patient's life signs are monitored continuously in order to detect medical situations prompting immediate action from attending medical professionals. The presence of seizure, essentially non-convulsive seizures, is often not detected nor diagnosed due to the complexity of having dedicated personnel reviewing streaming EEG or ECoG data in real-time.
An exciting and promising potential treatment to arrest seizures is Deep Brain Stimulation (DBS), where implanted electrodes deliver an electrical shock to the part(s) of the brain where the seizure originates. This electrical shock depletes neuro-transmitters locally, which, in turn, provides an effective barrier that prevents the ictal cascade to proceed beyond its originating point. The deep-brain stimulation treatment relies on the timely detection of the start of the seizure so that it can be applied before the manifestation of clinical signs. This treatment is applied only on a per need basis based on the early detection of the seizure.
Currently available methods of automated EEG analysis for epileptic activity detection have a number of significant disadvantages that prevent their wider utilization in clinical applications, and in particular, emergency and field applications. Such drawbacks include the following: 1) Susceptibility to environmental noise/interference and biological artifacts resulting in poor reliability; 2) Inability to preserve high signal quality resulting in poor reliability; 3) Lack of mobility and portability preventing easy handling, transport and wearability; 4) Lack of robustness and inability to withstand rough handling, water ingress and drop/vibration mechanical shocks; 5) Complex and time consuming application; 6) Complex interpretation of results requiring EEG expert knowledge; 7) Insufficient accuracy; and 8) Delays in detecting abnormal brain activity preventing timely diagnosis and intervention/prevention.
Better systems are needed for many types of applications such as mass casualty; battlefields; mobile hospitals; emergency intervention such as emergency rooms, on ambulances, on airplanes, on ships, and at accident scenes; and locations within a hospital, such as intensive care units and operating rooms. An inexpensive, rugged, and field-deployable means of automatically detecting the presence of EEG seizures and brain dysfunction, followed by rapid and aggressive management, is essential to ameliorate neuropathology from chemical and nerve agent exposure in a mass casualty situation. Accurate detection of a non-convulsive seizure using EEG analysis is of particular importance in treating victims of nerve agent poisoning. A patient could be experiencing status epilepticus (SE), yet due to depleted muscular stores of ATP, the patient will not manifest convulsions. If electrical SE is present, the patient should be given anticonvulsant. However, if no seizure is occurring or the patient is post-ictal, more anticonvulsant could compromise patient respiration and should not be administered. Hence, being able to accurately detect the presence of EEG seizures in such patients is critical for correct treatment.
It is therefore an object of the present invention to provide a system, monitor and method that meets all of the above needs. It is another object of the present invention that this method be inexpensive and/or rapid to conduct. It is still another object of the present invention that this method be usable by a person with no special medical training. It is still another object of the present invention that a patient's therapeutic treatment be more accurately determined based on the quantitative number or profile derived from the testing of the patient. The object of the present invention also is to alleviate the above limitations by providing a rugged and reliable system for acquisition and analysis of brainwaves obtained through intracranial or scalp electrodes (EEG or ECoG signals). The system is compact, ruggedized, watertight and lightweight, preferably easy to attach to a stretcher, IV pole or patient garment such as a belt. It further comprises means for mechanical shock and vibration protection. Such system also provides advanced hardware for shielding the electronics from harmful environmental noise and interferences, and advanced algorithms for the detection and removal of various artifacts that commonly corrupt neurophysiological signals. In addition, electronic means against cardiac defibrillation therapeutic shocks enhances system usage in emergency situations. Continuous measurements of electrode-skin contact and monitoring of signal quality further enhance the reliability of the acquired brainwaves. All the above means ensure the reliability of the system, which is important for guaranteeing the adoption of the system by non-EEG experts and medics, and thus its widespread use. Moreover, the system utilizes highly accurate algorithms for the timely detection of epileptic and other abnormal brain activities. These algorithms and methods are sensitive to such abnormalities. They are specifically designed such that they amplify abnormal activity, while minimizing normal background activity.